Recyclization of 1H-Pyrrole-2,3-diones into pyrazolo-[1,5-a]pyrimidines by the action of aminopyrazole

Full text of DOI:10.1134/S1070428009100273

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2009, Vol. 45, No. 10, pp. 1572–1573. © Pleiades Publishing, Ltd., 2009.
Original Russian Text © E.S. Denislamova, Z.G. Aliev, A.N. Maslivets, 2009, published in Zhurnal Organicheskoi Khimii, 2009, Vol. 45, No. 10,
pp. 1583–1584.
SHORT
COMMUNICATIONS
Recyclization of 1H-Pyrrole-2,3-diones into Pyrazolo-
[1,5-a]pyrimidines by the Action of Aminopyrazole
E. S. Denislamovaa, Z. G. Alievb, and A. N. Maslivetsc
a Institute of Technical Chemistry, Ural Division, Russian Academy of Sciences, Perm, Russia
b Institute of Chemical Physics Problems, Russian Academy of Sciences, Chernogolovka, Moscow oblast, Russia
c Perm State University, ul. Bukireva 15, Perm, 614990 Russia
e-mail: koh2@psu.ru
Received June 10, 2009
DOI: 10.1134/S1070428009100273
Reactions of monocyclic 1H-pyrrole-2,3-diones
with aminoazoles were not studied previously. We
found that methyl 1-aryl-3-benzoyl-4,5-dioxo-4,5-di-
hydro-1H-pyrrole-2-carboxylates Ia and Ib reacted
with an equimolar amount of 3-methyl-4-phenyl-1H-
pyrazol-5-amine (II) in boiling anhydrous 1,2-di-
chloroethane (reaction time 2–3 h according to the
TLC data) to give the corresponding methyl 7-aryl-
carbamoyl-6-benzoyl-2-methyl-3-phenylpyrazolo-
[1,5-a]pyrimidine-5-carboxylates IIIa and IIIb. The
structure of the products was proved by X-ray analysis.
closure of pyrimidine ring as a result of intramolecular
attack by the endocyclic nitrogen atom in the pyrazole
fragment on the ketone carbonyl group of the oxamoyl
fragment with elimination of water leads to final
product III.
The described reaction may be regarded as a new
synthetic approach to functionally substituted pyrazolo-
[1,5-a]pyrimidine system.
Methyl 6-benzoyl-7-(4-chlorophenylcarbamoyl)-
2-methyl-3-phenylpyrazolo[1,5-a]pyrimidine-5-car-
boxylate (IIIa). A solution of 1 mmol of compound Ia
and 1 mmol of pyrazole II in 10 ml of anhydrous
1,2-dichloroethane was heated for 3 h under reflux.
The mixture was cooled, and the precipitate was
filtered off. Yield 69%, mp 257–258°C (from 1,2-di-
Presumably, compounds III are formed via initial
addition of the primary amino group in pyrazole II to
the C2 carbon atom in the pyrrole ring of I. Subsequent
opening of the pyrrole ring at the N1–C2 bond and
HO
COPh
O
O
O
O
COPh
Ph
Me
NHAr
N
COOMe
NH
Ph
O
H
N
N
+
MeO
N
Ar
Ph
O
COOMe
H2N
N
H
N
N
NH
H
O
Me
Ar
N
Ph
Ia, Ib
II
Me
O
NHAr
O
O
N
N
Ph
Me
–H2O
MeO
N
Ph
IIIa, IIIb
Ar = 4-ClC6H4 (a), 4-MeOC6H4 (b).
1572

RECYCLIZATION OF 1H-PYRROLE-2,3-DIONES INTO PYRAZOLO[1,5-a]PYRIMIDINES
1573
chloroethane). IR spectrum, ν, cm–1: 3350 (NH), 1730
(COOMe), 1690 (CONH), 1665 (COPh). H NMR
ppm: 2.70 s (3H, Me), 3.65 s (3H, COOMe), 3.78 s
1
(3H, OMe), 6.94–7.88 m (14H, Harom), 11.21 s (1H,
NH). Found, %: C 69.39; H 4.53; N 10.91.
C30H24N4O5. Calculated, %: C 69.23; H 4.65; N 10.76.
spectrum, δ, ppm: 2.65 s (3H, Me), 3.60 s (3H, OMe),
7.24–7.97 m (14H, Harom), 11.45 s (1H, NH). 13C NMR
spectrum, δC, ppm: 14.05 (CH3), 52.96 (OCH3), 111.81
(C6), 121.13 (C3), 144.24 (C3′), 145.97 (C2), 156.41
(C5), 163.64 (CONH), 164.42 (CH3OCO), 190.60
(PhCO). Found, %: C 66.50; H 3.91; Cl 6.94; N 10.48.
C29H21ClN4O4. Calculated, %: C 66.35; H 4.03;
Cl 6.75; N 10.67.
The IR spectra were recorded on an FMS-1201
spectrometer from samples dispersed in mineral oil.
1
The H NMR spectra were measured on a Bruker
WP-400 instrument from solutions in DMSO-d6 using
tetramethylsilane as internal reference. The purity of
the products was checked by TLC on Silufol plates
using ethyl acetate as eluent; spots were detected by
treatment with iodine vapor.
Methyl 6-benzoyl-7-(4-methoxyphenylcarbam-
oyl)-2-methyl-3-phenylpyrazolo[1,5-a]pyrimidine-5-
carboxylate (IIIb) was synthesized in a similar way.
Yield 75%, mp 265–266°C (from 1,2-dichloroethane).
IR spectrum, ν, cm–1: 3340 (NH), 1725 (COOMe),
This study was performed under financial support
by the Russian Foundation for Basic Research (project
no. 07-03-96036).
1
1685 (CONH), 1665 (COPh). H NMR spectrum, δ,
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 45 No. 10 2009